Spool valve

ABSTRACT

A spool valve for automatically limiting the rate of flow of actuating fluid to an ON-OFF fast operating valve when the ON-OFF valve is closed and automatically increasing the rate of flow of actuating fluid as the ON-OFF valve begins to open.

United States Patent [19;

J aegtnes 11 3,794,292 Feb. 26, 19 74 SPOOL VALVE Karl 0. Jaegtnes,Aston, Pa.

Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: May 15, 1972 Appl. No.: 253,392

Inventor:

Assignee:

US. Cl 251/31, 137/596.l5', 251/25, 251/41 Int. Cl. Fl6k 31/383 Field ofSearch..... 137/625.6l; 251/25, 31, 36, 251/41 References Cited UNITEDSTATES PATENTS 9/1953 Herbst 251/31 X 2,934,765 4/1960 Carson l37/625.61

' Primary -ExaminerRobert G. Nilson Attorney, Agent, or Firm-F. J.Baehr, Jr.

57 ABSTRACT I A spool valve for automatically limiting the rate of flowof actuating fluid to an ON-OFF fast operating valve when the ON-OFFvalve is closed and automatically increasing the rate of flow ofactuating fluid as the QN-OFF valve begins to open.

4' Claims, 1 Drawing Figure DRAIN SUPPLY SPOOL VALVE This inventionrelates to quick operating valves for a steam turbine and moreparticularly a spool valve for controlling the flow of operating fluidto the quick operating valve.

To keep pace with the high rate of growth of power consumption, powercompanies have been installing larger and larger turbo-generator unitsoperating at high pressures and temperatures, or nuclear units, whichmake reheating the steam after it has partially expanded in a highpressure portion of the turbine economical. Utilizing reheat cyclesnecessitates installing stop and interceptor valves in the pipingbetween the reheater and the turbine as the reheater contains a largequantity of steam, which if allowed to expand through the turbine afterthe turbine loses its load could cause overspeeding and result ininternal damage to the turbine. The interceptor valve is controlled by acontroller responsive to the electricalload on the gen erator so thatthe interceptor valve anticipates losses of electrical load to beginshutting down the turbine at the first indication of loss of electricalload. Many of the disturbances, which cause a circuit breaker to openand which produce an indication of loss of load on the generator, willbe transient and clear themselves. Thus, it is common practice toprovide circuit breakers which automatically reclose one or more timesbefore finally locking themselves out. Quick operating valves functionto cut off the steam to the low pressure portion of the turbine as fastas possible by initiating closing of the intercept valve on stop valveupon loss of load.

Turbine steam valves are very large and being fluid actuated requirelarge quantities of fluid energy to separate them rapidly. To increasethe closing speed and to conserve the energy in the actuating fluid itis desirable to shut off the flow of operating fluid to the actuatorwhen the valves are being closed. However, to keep the actuator at aneven temperature and to insure that the system is primed, it isdesirable to allow a continuous limited flow of actuating fluid.

SUMMARY OF THE INVENTION In general, a spool valve, when .made inaccordance with this invention, comprises a housing having a bore and acounterbore, a spool member having a first cylindrical portion slidablydisposed within the bore and a second cylindrical portion slidablydisposed within the counterbore. The first cylindrical portion has acircumferential groove disposed therein and the spool valve furthercomprises a first and second port cooperatively associated with thegroove so that when the spool member is in one position the first andsecond ports are blocked by the first cylindrical portion and when inanother position the first and second ports are in fluid communicationwith the groove and with each other, a third port in fluid communicationwith the end of the come more apparent from reading the followingdetailed description in connection with the accompanying drawing, inwhich the sole FIGURE is a schematic diagram of a fluid control systemfor operating an ON- OFF valve in a steam line incorporating a spoolvalve .made in accordance with this invention.

DESCRIPTION on THE PREFERRED EMBODIMENT Referring now to the soleFIGUREin detail, it shows an ON-OFF steam valve 1 having a fluidactuator 3 comprising a piston or movable abutment 5 which is moved inone direction to close the valve by the bias of the spring 7 and movedin the other direction to open the valve by pressurized actuating fluidreacting against one side of the piston 5, the lower side as shown inthe drawings. A dump valve 9 has an inlet port 11 in fluid communicationwith the pressurized actuating fluid being supplied to the actuator 3and an outlet or drain port 13 in fluid communication with the drain andin fluid communication with the actuator 3. A valve plug 15 and seat 17is disposed in blocking relation between the inlet port 11 and outletport 13. The plug 15 is held in the blocking position against the biasof a spring -18 by actuating fluid supplied by a conduit 19 reactingagainst a piston 21 connected to the valve plug 15 by a valve stem 23. Asolenoid valve 25 or other means for shutting off the flow of fluid isdisposed in a drain concounterbore adjacent the bore, a fourth port influid communication with the end of the counterbore opposite the endadjacent the bore and means for placing the first port in fluidcommunication with the end of the bore opposite the end adjacent thecounterbore.

BRIEF DESCRIPTION OF THE DRAWINGS The objects and advantages of thisinvention will beduit 27 which is also in communication with the conduit19. The valve 25 is operable by a signal from a controller (not shown),which responds to a signal to close the steam valve 1 initiated by asudden loss of load or other operating condition. v

A spool valve 41 is disposed in a conduit 43 supplying pressurizedactuating fluid to the inlet port 1 .1 of the actuator 3. The spoolvalve 41 comprises a housing 45 having a bore 47 and acounterbore 49 anda spool member 50 having a first cylindrical portion 51 slidablydisposed within the bore 47 and a second cylindrical portion 53 slidablydisposed in the counterbore 49. The first cylindrical portion 51 has anannular groove 55 disposed therein. The ends of the spool member 50 haveprotrus'ions56 extending therefrom to provide a space between the endsof the spool member and the ends of the bore 47 and counterbore 49.

A first or inlet port 57 and a second or outlet port 59 arecooperatively associated with the groove 55 so that when the spoolmember 50 is in one position, all the way to the right, as shown in thedrawing, the inlet and outlet ports 57 and 59, respectively, are blockedby the first cylindrical portion 51 and when the spool member 50 is inanother position, all the way to the left, the inlet and outlet ports 57and 59 are in fluid communication with the groove 55 and with eachother.

A third or drain port 61 is disposed in the housing 45 so as to be influid communication with the end of the counterbore 49 adjacent the bore47.

A fourth port 63 is so disposed'in the housing 45 to be in fluidcommunication with the end of the counterbore 49 opposite the endadjacent the bore 47 and with a drain through the conduits 19 and 27 andvalve 25.

A duct 65 is so disposed in the housing 45 to place the inlet or firstport 57 in fluid communication with the fourth port 63. The duct. 65 hasflow restricting means 67 disposed therein.

A fifth port 69 is in fluid communication with the end of the bore 47opposite the end adjacent the counterbore 49 and a duct 71 places theport 69 in fluid communication with the inlet or first port 57.

A sixth port 73 is in fluid communication with the end of the bore 47opposite the end adjacent the counterbore 49 and in fluid communicationwith the second or outlet port 59 via a duct 75 and has a flowrestriction 77 disposed therein. The outlet port59 also has a flowrestriction 79 disposed therein. 7

The operation of the spool valve 41 and steam valve 1 is as follows:Assuming the solenoid valve 25 is closed; pressurized actuating fluid issupplied via the supply conduit 43. to the inlet port 57. Thepressurized fluid flows into opposite ends of the bore and counterborevia ducts 71 and 65, respectively. Since the area of the counterbore 49is larger than the area of the bore 47 and the end of the counterbore 49adjacent the bore 47 is in communication with a drain -via port 61, thespool member 50 moves from the one'position shown in the drawing toanother position, wherein the groove 55 registers with the inlet andoutlet ports 57 and 59 respectively, allowing pressurized fluid to flowat a high rate via conduit 43 to the inlet port 11 of the valve actuator3.

Actuating fluid simultaneously flows via conduit 19 to operate thepiston 21 and seat the plug 15 shutting off the drain port 13 andallowing pressurized fluid entering the actuator 3 via port 11 to movethe piston upwardly opening the steam valve 1.

Upon receiving a signal from the controller to close the steam valve 1,the solenoid valve 25 opens and with the assistance of the restriction67 drains fluid rapidly from one side of the piston 21 allowing thespring 18 associated therewith, to unseat the plug and drain actuatingfluid from the actuator 3 causing the spring 7 to close the steam valve1 rapidly.

Simultaneously with the draining of actuating fluid from one side of thepiston 21 actuating fluid is drained from the end of the counterbore 49opposite the end adjacent the bore 47 causing an unbalance of the spoolmember 50 as pressurized fluid is still being supplied to the end of thebore opposite the end adjacent the counterbore which causes the spoolmember 50 to move to the one position, to the right as shown in thedrawing, wherein the inlet and outlet ports 57 and 59, respectively, areblocked by the first cylindrical portion 51 of the spoolmember 50reducing the flow of actuating fluid to a limited rate which assists inclosing the steam valve rapidly.

The spool valve hereinbefore described advantageously reduces the fluiddemand from the supply system when the ON-OFF valve is closed, but stillpasses sufficient fluid to keep the system primed and cooled.

What is claimed is:

1. A spool valve comprising a housing having a bore and a counterbore, aspool member having a first cylindrical portion slidably disposed withinthe bore and a second cylindrical portion within the counterbore, saidfirst cylindrical portion having a circumferential groove disposedtherein, a first port and a second port cooperatively associated withthe groove so that when the spool member is in one position, the firstand second ports are blocked by the first cylindrical portion and whenin another position, the first and second ports are in fluidcommunication with the groove and with each other, a third port in fluidcommunication with the end of the counterbore adjacent the bore, afourth port in fluid communication with the end of the counterboreopposite the end adjacent the bore, means for placing said first port influid communication with the end of the bore opposite the end adjacentthe counterbore, means for placing the end of the bore opposite the endadjacent the counterbore in fluid communication with the second port,and flow restricting means disposed to restrict the flow between thefirst and second portion when the spool member is positioned to blockthe flow between said first and second port.

2. A spool valve as setforth in claim 1 and further comprising means forplacing the first port in fluid communication with the fourth port andflow restricting means disposed in the means forplacing the first portin fluid communication with the fourth port.

3. A spool valve as set forth in claim 1 wherein the third port is adrain port.

4. A spool valve as set forth in claim 1, wherein the second port is anoutlet port and is in communication with an outlet duct having flowrestricting means disposed therein.

1. A spool valve comprising a housing having a bore and a counterbore, aspool member having a first cylindrical portion slidably disposed withinthe bore and a second cylindrical portion within the counterbore, saidfirst cylindrical portion having a circumferential groove disposedtherein, a first port and a second port cooperatively associated withthe groove so that when the spool member is in one position, the firstand second ports are blocked by the first cylindrical portion and whenin another position, the first and second ports are in fluidcommunication with the groove and with each other, a third port in fluidcommunication with the end of the counterbore adjacent the bore, afourth port in fluid communication with the end of the counterboreopposite the end adjacent the bore, means for placing said first port influid communication with the end of the bore opposite the end adjacentthe counterbore, means for placing the end of the bore opposite the endadjacent the counterbore in fluid communication with the second port,and flow restricting means disposed to restrict the flow between thefirst and second portion when the spool member is positioned to blockthe flow between said first and second port.
 2. A spool valve as setforth in claim 1 and further comprising means for placing the first portin fluid communication with the fourth port and flow restricting meansdisposed in the means for placing the first port in fluid communicationwith the fourth port.
 3. A spool valve as set forth in claim 1, whereinthe third port is a drain port.
 4. A spool valve as set forth in claim1, wherein the second port is an outlet port and is in communicationwith an outlet duct having flow restricting means disposed therein.